The broadcaster admitted earlier this month that it accessed the accounts of "canoe man" John Darwin and his wife Anne, as well as those of a suspected paedophile.

Sky News defended its actions as being in the public interest and said it amounted to "responsible journalism".

Ofcom confirmed on Monday that it is investigating the "fairness and privacy issues" raised by the hacking.

A spokesman for the media regulator said today: "Ofcom is investigating the fairness and privacy issues raised by Sky News'
statement that it had accessed without prior authorisation private email accounts during the course of its news investigations.

"We will make the outcome known in due course."

Ofcom code states that "any infringement of privacy in programmes, or in connection with obtaining material included in programmes, must be warranted".

The regulator has a variety of potential sanctions for breaches of its code, depending on the severity.

They range from a warning to a fine or the revocation of a licence in the most serious circumstances.

Sky News said previously the evidence discovered through the hacking of the Darwins' emails was handed to police.

Darwin faked his own death in a canoeing accident in 2002 so his wife could claim hundreds of thousands of pounds from insurance policies and pension schemes.

The hacking of the emails of the suspected paedophile did not lead to the publication or broadcast of any material.

Cole is leaving the company but he said his decision to leave Sky News after 17 years was "unrelated to the Darwin story".

A spokeswoman for Sky News said today: "As the head of Sky News, John Ryley, said earlier this month, we stand by these actions as editorially justified.

"The Crown Prosecution Service acknowledges that there are rare occasions where it is justified for a journalist to commit an offence in the public interest.

"The Director of Public Prosecutions Keir Starmer told the Leveson inquiry that 'considerable public interest weight' is given to journalistic conduct which discloses that a criminal offence has been committed and/or concealed."